It is well known that the driving abilities, techniques and habits of vehicle operators vary considerably from person to person. Driving techniques used by the same person may also vary considerably depending on road and weather conditions.
Although driving abilities may be related to such factors as age, experience, physical condition and other factors which are difficult to change, there is a large body of statistical evidence gathered by insurance companies and public safety authorities which clearly indicates that certain driving techniques or habits are far safer than other habits.
For example, the manner in which a vehicle operator applies the vehicle brakes obviously affects vehicle stopping distance and, in many cases, driving safety. The manner in which the brakes are applied varies considerably, even with the same driver, depending on road conditions, required stopping distance, vehicle weights and loading and other factors.
One critical factor in accident avoidance is brake application in rapid stop or "panic" situations. In this type of situation many drivers tend to over apply the brakes, resulting in locking of the vehicle wheels and skidding. It is well-known that traction between the vehicle tire and the road is greatly reduced when the tire is skidding from the traction which is available when the wheel is rotating. When the traction is reduced the driver tends to apply the brakes even harder resulting in more wheels locking and even further reduced traction. This situation is further exacerbated by adverse road conditions such as wet or icy pavement. These road conditions increase the likelihood that the vehicle wheels will experience different traction and therefore the likelihood that one or more wheels will lock. In addition, they also increase the likelihood of loss in directional control which also results from wheel skid.
In an effort to overcome this problem, "anti lock" braking systems have been developed. These systems utilize a central computer system with rotation sensors at each wheel. When a wheel begins to lock and initiate a skid, the computer senses the reduction in wheel rotation frequency and momentarily releases the brake on that wheel. Thus, maximum braking efficiency is maintained, but the wheels are not allowed to lock. The anti-lock braking system is very effective in preventing wheel skid in rapid stop situations. However, it has only recently become available in most vehicles. In addition, it is costly and generally requires disk type brakes on all vehicle wheels. Consequently, the anti lock braking system cannot be easily retrofitted into existing vehicles which are not already equipped for such operation.
Accordingly, in the interest of safety, a considerable effort has been made to effectively train vehicle operators to use "safe" driving habits and techniques. One of these techniques is called brake "stabbing" or "pumping" in which the vehicle operator repeatedly applies and releases the vehicle brakes. This technique either prevents the wheels from locking or minimizes the time during which the wheels are locked, thereby avoiding skidding problems. When used properly, the technique is highly effective especially with large, heavy vehicles, such as tractor-trailer rigs, in adverse road condition situations.
However, the brake stabbing technique is not entirely straightforward as its effectiveness is largely dependent upon the exact brake pressure and timing used by the operator during the technique. Generally, it is difficult for the driver to tell which wheels, if any, have locked and the length of time during which the wheels have locked and, therefore, it is difficult for an operator to evaluate his own performance in braking technique.
Consequently, the technique takes some training and practice for fully effective use. However, there are no prior art methods for testing or quantifying an operator s skill in using the technique. Frequently, driver evaluation has been measured by having a driving instructor or trainer ride with the driver in a test vehicle while the driver drives the test vehicle over a specially designed test track. The trainer can then evaluate the driver's technique during actual performance. Alternatively, a practice driving session can be photographed or videotaped for later evaluation. These indirect methods only quantify overall vehicle performance and do not directly measure the driver's techniques and skills.
Accordingly, it is an object of the present invention to provide a sensing device which can directly measure an operator's driving performance.
It is another object of the present invention to provide a sensing device which can quantitatively measure an operator's driving performance.
It is still another object of the present invention to provide a sensing device which can quantitatively measure an operator's braking technique.
It is yet another object of the present invention to provide a sensing device which can easily be connected to the braking system of many conventional vehicles.
It is a further object of the present invention to provide a sensing device which is relatively simple to use.